Dibasic acid drying oils



Patent'ed Apr. 27, 1948 OFFICE mnasrc ACID name OILS Latimer D. Myers, Cincinnati, and Victor J.

Muckerheide,

Silverton,

Ohio, aesignora to Emery Industries, Inc., Cincinnati, Ohio, a cornotation of Ohio No Drawing. Application November 6, 1942,

Serial No. 464,792

23 Claims. (01. zoo-464.8)

This invention relates the drying properties of oils of the so-called drying and semi-drying" types. It is directed particularly to a method of treating such oils for the purpose of accelerating the speed with which films of the oil dry and harden when exposed to air and heat. It is also an objective of the present invention to improve the characteristics of water resistance and impermeability of films produced from such oils.

The invention, briefly, is based upon a discovery we have made that these desirable results may be obtained by treating the oils at elevated temperature with a di-basic aliphatic acid. In thecourse of this treatment, speaking generally and with with some conjecture, it is believed that the dibasic acid selectively displaces saturated and mono-unsaturated components of the oil; that is, selectively displaces non-drying constituents. At any rate non-drying components of the oil are liberated and these are removed from the oil, as by distillation. The drying and film forming properties are thus improved.

In the past, a variety of methods has been proposed for eifecting the non-drying constituents, for example, to remove them or sequester them in such condition that the unsaturated drying components may proceed to dry when exposed in film formation. However, one of the chief difficulties in these methods has been to isolate or modify the non-drying constituents without also adversely afiecting the unsaturated compounds to which the oil owes its drying properties. -In the present invention the treatment, so far as we have been able to determine, is substantially selective, saturated bodies such as stearic acid, and monounsaturated bodies such as oleic acid being displaced from the glyceride compounds from which the oil is made up, while the di-basic acids either enter the reaction to form other compounds which have improved dryingcharacteristics or at least do not impair the drying characteristics of the remaining doubly and triply unsaturated bodies.

In'the process of the present invention, therefore, the oil to be improved is heated with the dibasic acid treating reagent to eflect reaction of the two. Following this operation, the non-drying components which have been displaced or liberated are removed from the oil and recovered as to a method of improving free fatty acids. Thus,

a typical procedure of the present invention is as follows:

Exnrru! is heated rapidly to a temperature of approximately 300 C. in an atmosphere of carbon dioxide. After heating for one hour under atmospheric pressure, the liberated tree iatty acids are removed by vacuum distillation. The distillation may continue for about 1 /2 hours, or continue until the acid value of the still contents is reduced to approximately 8.1. The distillate, which in a I typical instance amounted to 20.4% of the starting materials. is soluble in petroleum other showing freedom from di-basic acids; the modified linseed oil withdrawn from the still had a viscosity of 34 poises and after the addition of drier a film on tin was completely dry in 24 hours, whereas a sample of the same linseed oil which had been bodied and to which the same amount of drier had been added required 72 hours to dry completely.

There are several controls to be observed in the practice of thainvention; these are briefly! the di-basic acid selected as treating reagent, the

quantity used and the time and temperature of distillation. The process is adapted to be applied to oils of the drying and semi-drying types including linseed oil, soya bean oil, perilla, fish oils such as sardine oil, menhaden and the like. Ohviously, these oils diil'er in composition from one another, even from batch to batch, and the final products, therefore, will also differ in their properties.

As previously indicated. the di-basic acid constituting the treating reagent is caused to react displacing the non-drying components of the oil being treated and these are then taken ofi by distillation. It is requisite, therefore, that the dibasic acid have a boiling point above that of the displaced bodies; otherwise, the di-basic acids would be volatilized and removed to no useful end. Az elaic acid, sebacic acid, and adipic acid are representative di-basic acids which have this propc ty. All such acids conveniently may be classifled as di-basic aliphatic acids having a vapor pressure below that of the non-drying bodies which they displace upon being heated with a drying or a semi-drying oil. It is to be noted that this classification excludes phthalic acid or its anhydride which, though it is a common di-basic acid, has a vapor pressure so high that it may not be used for the present purpose because of sublimation. However, aromatic di-basic acids may be employed-in the practice of the present invention if their boiling point is sufficiently high; this characteristic, for example, may be obtained by the addition of side chains.

The di-basic acids just described may be obtained from any suitable source, sebacic acid, for example, from castor oil, and azelaic by the oxidation of unsaturated fatty glycerides or fatty acids like oleic. In place of adding di-basic acids per se to the oil which is to be treated, di-basic acids found in admixture with other products resulting from the oxidation of predominantly unsaturated fatty glycerides and their acids may be used directly in the present process. For example, one may oxidize oleic acid, remove the oxidizing reagent, and proceed to use the resulting mixture without endeavoring to isolate the resulting dibasic acid, azelaic, from the other mono-basic or di-basic acid constituents which also were formed during oxidation. In this case, the azelaic acid (and other di-basic acids which may be present in smaller proportion) react in the indicated manner with the oil being treated while the presence of the mono-basic and by-product acid compounds not only does not impair the result, but these simultaneously are separated from one another. It is to be observed in this respect that the present process is useful as a means of separating mono-basic and by-product acid compounds. The use of such mixed oxidation products is particularly economical inasmuch as separation costs are avoided and non-drying oils which are abundant in oleic acid may be used to contribute to the manufacture of drying oils of greater value. Further details of these aspects of the present invention are. given at a later point in the specification, but it also may be stated here that in place of adding either di-basic acid per se or mixed products containing di-basic acid, the invention also embraces the process in which free di-basic acids are produced, in situ, in the oil to be improved and from a portion of it. For instance, in this case, a part only of the oil which is to be treated is oxidized to form di-basic acids: following this treatment the remainder of the oil is added and the total is subjected to heat during which non-drying components are displacedby the liberated di-basic acids and the latter are then distilled away. This method is particularly useful for. semi-drying oils like soya bean oil.

The quantity of di-basic acid employed in the invention is an amount suflicient to displace all, or substantially all of the monounsaturated acids as, for example, oleic. We have determined that one part of azelaic acid, which is a representative di-basic acid, will displace substantially 2.9 parts of constituentto be removed, calculated as oleic acid, which is a representative monounsaturated non-drying constituent. This relationship, therefore, serves as a useful guide in determining the quantity of di-basic acid to be added to the oil, with appropriate adjustments in this ratio being made on a mol to mol basis where the non-drying constituent to be liberated is other than oleic acid. Thus, the quantity of di-basic acid employed in the practice of the presentinin the neighborhood of 300 to 340 C. and usually,

for a period of about an hour. The rate of heating is not of any great importance except of course that it should not be so rapid that there is a tendency for the oil to become overheated, nor should it be so slow that bodying proceeds beyond a desirable point. There is, also, some tendency of the oil to darken in color when heated for longer periods. A blanket of a non-oxidizing gas such as carbon dioxide or nitrogen employed in the treating chamber helps to exclude air and minimizes this tendency,

The reaction may take place directly in a still pot or a vessel arranged for vacuum distillation. Thus, when the reaction period is ended, a vacuum is drawn and the displaced vapors are cooled and condensed for recovery. The distillate, gen erally speaking, is free fatty acids and the iodine value of the distillate represents free fatty acids having substantially lower iodine value than the iodine value of the oil being treated, for example, in the case of linseed oil the iodine value of the displaced acids is 30 to 40 points lower than the iodine value of the original oil. Distillation is continued until free fatty acid content of the oil in the still is brought to the desired point, usually between 2 and 5%. When the free fatty acid content of the oil has been reduced sufliciently, the oil is cooled and is then ready for use.

On the other hand, knowing that one part of a'zelaic acid can displace 2.9 parts of oleic acid from the oil being treated, the quantity of distillate recovered, in relation to the quantity of dibasic acid added, may be used as a general guide to indicate the point at which distillation may be of determining the point at which distillation is V to be stopped the pelargonic acid and by-product acids must also be taken into consideration. In any event the main point is to continue distillae tion until the 011 exhibits the desired improved drying properties. If distillation is stopped too soon, free fatty acids displaced by the di-basic acids will still be present in the oil and may impair its drying qualities.

It is not usually desirable to continue distilla tion until the last traces of free fatty acid are re moved because the continued heating will increastzthe body of the oil'beyond the desired point. Generally speaking, distillation is continued until no more appreciable quantities of fatty acid are distilled from theoil being treated and until the residue in the still has the desired acid value.

Other typical examples illustrating the practice of the invention are as follows:

EXAMPLE I! Treatment of soya bean oil with azelaic acid 24 parts of azelaic acid are added to parts of refined soya bean oil contained in a still arranged for vacuum distillation. The mixture is mated to 300 C. for 1 hour in an atmosphere of until the pressure in the still has dropped to 50 mm, of mercury and at the same time the temperature is gradually raised to 325 C. in order to provide a uniform rate of distillation of the liberated fatty acids.

Distillation is continued until the acid value of the still contents has dropped to 1.0 and the viscosity has reached 30 poises. The distillate which amounts to 28.8% of the total starting materials consists of fatty acids with an average combining weight of 278 and contains less than .1% of azelaic acid. v

The oil remaining in the still is a dark straw color and is used to prepare 20 gallon varnish having a viscosity of two poises. This varnish is completely dry in 18 hours-compared to 30 hours required for an identical varnish which has been prepared from soya bean oil, which has been bodied but not otherwise treated.

The dried varnish panels are immersed in boiling water for 15 minutes- After this treatment the varnish prepared from the azelaic treated soya bean oil shows only a trace t whitening while the varnish prepared from the untreated soya is completely white.

Exlmrnl: III I Treatment or sardine oil/with azelaic acid Azelaic acid, 40 parts and refined sardine oil, 700 parts, are heated in a still to 300 C. in an atmosphere of CO: for 45 minutes and then subjected to distillation under a vacuum of mm. of mercury until the acid number of the still content has been reduced to 2.2. The final temperature is 315 C. i

The distillate amounts to 14.1% of fatty acids having an iodine value of 97.2. The still residue has a viscosity or 33.0 poises and with the addition of an appropriate amount of drier. becomes completely dry in 24 hours. A comparative test on untreated sardine shows drying is very slow and even after 120 hours the film is slightly tacky.

ExaMrLn IV Treatment of sardine oil with adipic acid A mixture of j 1 Parts Sardine oil r. 100 Adipic acid 20.

is distilled under vacuum for a period of 30 min- Exaurnr: V

Treatment of sardine oil with. sebacic acid A mixture of Y Parts sardine oil 100 Sebacic acid is heated in a vacuum still, the temperature being raised from 20 C. to 340C. in minutes.

i The distillate which is obtained contains 22.5 parts of fatty acids having an iodine value of 87.0 and 6.7 parts of sebacic acid, indicatingthat approximately $5 of the sebacic acid used has reacted with the sardine oil.

The residue amounting to 90.6 parts is a heavy bodied oil which with the addition of drier dried to a hard film in 24 hours, compared to over 120 hours required for untreated oil.

EXAMPLE VI Treatment or linseed oil with mixed products oxidation The mixedoxidation product is prepared by treating oleic acid with an oxidizing reagent consisting preferably of one part of chromic acid. 2 parts of concentrated sulphuric acid and 4 parts of water in the proportion of approximately 50 parts of oleic acidto approximately 472 parts of oxidizing reagent. During the oxidation of the oleic acid the temperature is not allowed to exceed approximately 90 C. when the reaction is complete the spent solution is drawn ofl and the oxidizing mixture then consists of approximately 33-35% of di-basic acids, chiefly azelaic, -45% of mono-basic acids, chiefly pelargonic, and about 20-25% of low iodine fatty acids. This mixture usually is green in color and it is desirable that this green color be removed by acid washing, otherwise the oil resulting from treatment with the product will he very dark. A mixture of 600 parts ,of refined linseed oilof which the drying properties are to be improved and 150 parts of these mixed oxidation products of oleic acid are heated in a vacuum still for 1 hour at 300 C. in an atmosphere of. carbon dioxide. The pressure is gradually reduced to remove 10w boiling acids, the first distillate amounting to 61.8

parts having a combining weight of 159 is obtained in 1 hour at a final vacuum of mm.

The distillation is continued for 1% hours, the temperature being raised to 318 C. and the vacuum dropped to 5 mm. and 197.2 parts of distillate having a combining weight of 269.2 collected.

The residue has an acid value of 1.0 and a viscosity of 45 pulses.

After adding drier, films are formed on tin which dry in 24 hours compared to 72 hours for'bodied untreated linseed oil.

EXAMPLE VII Improving drying properties of soya bean Oil, by I partial oxidation 400 parts of refined soya'bean oil (125.1 I. V.)

is treated with 1295 parts of a chromic acid solution consisting of 1 part chromic oxide, 2.5 parts of sulfuric acid, and 4 parts of water, at il0--90 C. until the chromic acid is completely reduced as indicated by the green color of the solution.

Themixture is allowed to stand for about 1 hour to obtain a clear separation of the oily top layer amounting to 397 parts.- The oily layer is drawn oil! and heated and agitated with parts of concentrated hydrochloric acid to remove product containing di- 1 v J 7 cosity of the oil remaining in the still has-increased to 29 poises and the acid number has dropped to 1.0. The distillate consists of fatty acids having an iodine value of 92.8 and represents 18.4% of the original oil.

.1% lead and .0l% cobalt (as naphthenates) are added to the residual oil which then dries completely in 42 hours while bodied soya bean oil, 27 poises, containing the same percentages of driers, is still quite tacky after '72 hours.

Exsuru: VIII Improving drying of cottonseed oil Of a total batch of 380 parts of cottonseed oil. 115 parts thereof are oxidized with 1854 parts of chromic acid solution; the spent oxidizing solution and traces of chromic salts are removed, as described in the preceding example. 106 parts of mixed oxldating products are recovered from this treatment and these mixed oxidating prodnets are added to the 265 parts remaining from the original batch of cottonseed oil. This admixture is heated to 300 C. for 45 minutes under atmospheric pressure. Vacuum is then gradually applied and the temperature raised slowly until after 2 and /2 hours the temperature has been increased to 325 C. and the pressure reduced to 5 mm; 104.8 partsof distillate consisting of fatty acids having an iodine value of 77.6v is obtained. The residue in the still which has an acid number of .5, although not possessing as good drying properties as other oils processed in the same manner, still dries in 30 hours to yield a fairly good film, while the untreated oil shows scarcely any signs ofv drying even after days and 'could hardly be considered usable in even the cheapest paints.

Exams: 1X

Improving the drying properties of soya bean by oxidizi g graft remove chromic salts and'the traces of mineral acidity removed by neutralization with alkali, 87.6

1 parts are recovered.

The oxidized portion and the 350 parts of untreated oil are heated to 300 C. for-1 hour and then the free fatty acids distilled at 25 mm. during a period of 2 and /2 hours until the oily residue in the still has been reduced to 2.2 acid value and has bodied to 21.0 poises.

with the addition of .1% lead and .01% cobalt, this oil dries in 24 hours while bodied soya bean oil with the same amount of drier is still quite tacky after '12 hours.

Having described our invention, we desire to be limited only by the substance of the claims which follow:

1. The method of liberating non-drying constituents from an oil in the class consisting of drying and semi-drying oils for the purpose of improving its drying properties, which method comprises treating the oil at elevated temperature with an aliphatic di-carboxylic acid to displace non-drying constituents from the oil and which itself has a vapor pressure lower than the vapor pressure of the displaced constituents, and then '8' I liberating the non-drying constituents by distilling them from the oil.

2. The method of improving the drying properties of linseed oil which comprises treating the linseed oil with azelaic acid at an elevated temperature sufllciently high to permit the azelaic acid to displace non-drying constituents of the linseed oil. and removing the displaced constituents from the oil by distillation.

3. The process of improving the drying properties of linseed oil which comprises treating linseed oil at elevated temperature with an aliphatic dicarboxylic acid to displace non-drying constituents from the linseed oil and which itself has a vapor pressure lower than the vapor pressure of the displaced constituents, and then removing the displaced constituents by vacuum distillation.

4. The process of improving the drying properties of linseed oil which comprises treating linseed oil at a temperature above approximately 300 'C. with azelaic acid to effect displacement of non-drying constituents of the linseed oil by the azelaic acid in such proportions that one molecular part of azelaic acid is present for substantially each 2.9'parts of non-drying constituent to be removed, calculated as oleic, and then distilling the displaced non-drying constituents from the oil.

5. The process of improving the drying properties of linseed oil which comprises treating linseed oil at a temperature above approximately 800 C. with azelaie acid and in an atmosphere of an inert gas to eilect displacement of nondrying constituents of the linseed oil by the asslaic acid, in such proportions that one molecular part of azelaic acid is present for substantially each 2.9 parts of non-drying constituent to be removed. and then distilling the displaced nondrying constituents from the oil.

6. The process of liberating monounsaturated non-drying constituents from oils of the class of drying'and semi-drying oils for the purpose of improving their drying properties, which process comprises subjecting the oil at elevated temperature to a treating reagent comprising an allphatic di-carboxylic' acid to displace monounsaturated non-drying constituents from the oil at elevated temperature and having a boiling point above the elevated temperature at which the monounsaturated n0n-drylng.constitlients are displaced, and then removing the displaced con stituents;

"I. The process of improving the drying properties of soybean oil which comprises treating the soybean oil with azelaic acid at an elevated temperature which is sufliciently high to enable the azelaic acid to displace non-drying constituents from the soybean oil but which elevated temperature is below the boiling point of azelaic acid, andthen removing the displaced constituents by vacuum distillation.

8. The process of improving the drying properties oi soybean oil which comprises treating soybean oil with azelaic acid in the proportion f approximately 24 parts of azelaic acid to each parts of soybean oil at a temperature of at least approximately 300 C. but below the boiling point of azelaic acid, thereby effecting displacement of non-drying constituents from the soybean oil by the azelaic acid, and then liberating the displaced non-drying constituents from the stituents from an oil of the'class temperature and under an inert atmosphere, the said temperature being suillciently high to enable the azelaic acid to displace non-drying constituents from the fish oil, and being below the boiling point of the azelaic acid, and then liberating the displaced constituents from the flsh oil by vacuum distillation.

10. A method or improving the drying properties of sardine oil which comprises treating sardine oil with azelaic acid in the proportion of approximately 700 parts of soybean oil to about each 40 parts of azelaic acid at an elevated temperature which is sufilciently high to enable the azelaic acid to displace non-drying constituents from the fish oil but which is below the boiling point of the azelaic acid for a period of time suflicient for the azelaic acid to displace nondrying constituents from the fish oil, and then separating the displaced components from the sardine oil by vacuum distillation.

11. The method of improving the drying properties of fish oil which method comprises treating the oil to be improved with a di-basic aliphatic acid at an elevated temperature, the said di-basic acid being a member selected from the group comprising azelaic acid, sebacic acid and adipic acid and the temperature of the treatment being sufilciently high to enable thedibasic acid to displace non-drying constituents from the oil but also being below the boiling point of the di-basic acid and removing the non-drying constituents after they have been displaced, by vacuum distillation.

12. A method of liberating non-drying constituents from sardine oil which method comprises treating the sardine oil with adipic acid in the proportion of approximately parts or adipic acid to each 100 parts of sardine oil at a temperature elevated to enable the adipic acid to displace non-drying constituents from the sardine oil but at a, temperature below the boiling point of adipic acid and for a period of time sufilcient for the adipic acid to displace nondrying components from the sardine oil, and then separating displaced non-drying constituents from the sardine oil by vacuum distillation.

13. A method or liberating non-drying conconsisting of drying and semi-drying oils, which method comprises treating the oil witnsebacic acid at an elevated temperature which is below the boiling point of sebacic acid and for a period of time sufiicient for the sebacic acid to displace nondrying constituents from the oil. and then separating the displaced constituents from the oil by distillation. I

14. The-process of improving the drying properties of an 011 selected from the class consisting of drying and semi-drying oils, which method comprises subjecting a portion of the oil to an oxidizing reagent capable of oxidizing unsaturated compounds in said portion to cleave the double bond and form di-basic acids, removing spent and unspent portions or the oxidizing reagent from the oxidized oil and then mixing the oxidized portion of the oil with the unoxidized remainder of the oil and heating the two together at an elevated temperature for a period of time sufflcient ior di-basic acids present in the oxidized oil to displace non-drying constituents from the unoxidized portion, of the oil. whereby the drying properties of the unoxidized portion of the oil are improved.

15. A method oi. improving the drying properties of a batch or soybean oil which comprises subjecting a portion only or the total batch of soybean oil with an oxidizing reagent capable of oxidizing unsaturated compounds in said portion to cleave the double bond and form d i-basic acids, separating spent and unspent oxidizing reagent from the oil which has been subjected to oxidation, and then adding this oil to the remainder of the batch of soybean oil and heating the two together at an elevated temperature sufilcient for the'di-basic acids contained in the oxidized portions of the oil to displace monounsaturated contituents from the unoxidized portion of the batch whereby the drying properties of it are improved.

16. A method of improving the drying properties of an oil selected from the class consisting of drying and semi-drying oils, which method comprises subjecting an oil containing doubly and tripiy unsaturated glycerides to an oxidizing agent capable of oxidizing unsaturated compounds to cleave the double bond and form dibasic acids in admixture with mono-basic and byproduct acids, adding said mixed oxidation products including said di-basic acids to said oil which ,is to be improved and heating the two together at an elevated temperature for -a period of time ties of an oil selected from suflicient for the di-basic acids contained in said mixed oxidation products to displace from the oil being treated mono-unsaturated non-drying constituents, and then separating said displaced constituents thereby obtaining 9. treated oil have ing improved drying properties.

17. The process of improving the drying properties oi. an oil selected from the class consisting of drying and semi-drying oils, which method comprises subiecting'a portion of the oil to an aqueous chromic acid solution to oxidize unsaturated compounds in said portion to cleave the double bond and form di-basic acids, removing spent and unspent portions of the aqueous chromic acid from the oxidized oil and then mixing the oxidized portion of the oil with the un-' oxidized remainder of the oil and heating the two together at an elevated temperature for a period or time sunicient for di-basic acids present in the unoxidized oil to displace non-drying constituents from the unoxidized portion of the oil, whereby the drying properties of the unoxidized portion of the oil are improved.

18. A. method of improving the drying properties of a batch of soybean oil which comprises subjecting a portion only Of the total batch of soybean oil to an aqueous chromic acid oxidizing reagent to oxidize unsaturated compounds in said portion to cleave the double bond and form dibasic acids, separating spent and unspent oxidizing reagent from the oil which has been sub jected to oxidation, and then adding this oil to the remainder of the batch of soybean oil and heating the two together at an elevated temperature suflicient for the di-basic acids contained in the oxidized portion or the oil to displace mono-unsaturated constituents from the unoxidized portion of the batch whereby the drying properties of it are improved.

19.. A method of improving the drying properthe class consisting of drying and semi-drying oils, which method comprises subjecting an oil containing doubly and triply unsaturated glycerides to an aqueous chromic oxide oxidizing agent to oxidize unsaturated compounds to cleave the double bond and form di-basic acids in admixture with monobasic and by-product acids, adding said mixed oxidation products including said di-basic acids 11 to said oil which is to be improved and heating the two together at an elevated temperature for a period of time sufllcient for the di-basic acids contained in said mixed oxidation products to displace from the oil being treated mono-unsaturated nondrying constituents, and'then separating said displaced constitu nts thereby obtaining a treated oil having improved drying properties.

20. As a. new product, a drying oil which comprises an oil selected from the class consisting of ,drying and semi-drying oils in which nondrying constituents are replaced by an aliphatic d-i-carboxylic acid having a vaporpressure lower than the vapor pressure of thereplaced non- I drying constituents.

than the vapor pressure or the replaced non-drying con-' stituents.

23. As a new product, a drying oil which comprises flsh oil in which non-drying constituents are replaced by an aliphatic di-carboxylic acid having a vapor pressure lower than the vapor pressure of the replaced non-drying constituents.

LA'IIMER D. MYERS. VICTOR J. MUCKERHEIDE.

REFEMiNCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,873,513 Van Loon Aug. 23, 1932 2,040,461 Bonney May 12, 1936 2,050,930 De Groote Aug. 11, 1936 2,178,874 Hervey Nov. 7, 1939 2,182,332 Barsky Dec. 5, 1939 2,203,680 Elilngboe -1 June 11, 1940 2,292,950 Lcder Aug. 11, 1942 2,319,507 Krumbhaar May 18, 1943 

